JPH02215282A - Moving body tracking device - Google Patents

Abstract

PURPOSE:To speedily track a moving body with a simple constitution by executing a focusing in a phase difference detection system and, thereafter, tracking the movement of an objective body in a contrast detection system by means of a video signal with an area sensor. CONSTITUTION:A tracking objective body is captured, and an AF lock switch 27 is closed. Then, a CPU 15 is operated, a distance up to the tracking objective body is detected in the phase difference system, a photographing lens 2 is driven, and a focus matching is executed. By the focus detection in the system, the focus matching is speedily executed. Next, the video signal output of an area sensor 5 is analyzed, and the movement of the tracking objective body is detected. When the movement of the tracking objective body is detected, the high band frequency components of the video signal are detected by an HPF 10, the detecting signal of the HPF 10 is A/D-converted and, thereafter, stored into an image memory 12. In a CPU 13 connected to the memory 12, the high band frequency components of the video signal are utilized, a calculation for the focus matching is executed, and thereby, the focus matching in the contrast system is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a moving object tracking device, and more particularly to a moving object tracking device that automatically tracks and focuses a moving object in a camera, particularly a video camera.

[Prior Art] In a moving object tracking device used when photographing a moving object with a video camera, etc., the problem is how to detect the moving object.
The method was published in ``Detection and Tracking of Moving Objects'' in October 1978.

Regarding automatic tracking of moving objects, Japanese Patent Application Laid-Open No. 60-2
Many such methods are disclosed in Japanese Patent No. 49477 and the like.

The automatic tracking focus detection device disclosed in Japanese Patent Application Laid-Open No. 60-249477 has a means for movably setting a tracking field of view, an extraction means for extracting features of an object to be ranged with respect to this tracking field of view, and storage means for storing the extracted features; means for detecting the presence or absence of relative movement of the object based on the features of the object extracted by the extraction means and the features stored in the storage means; It consists of a means for moving the distance measurement field of view to track the movement of the object according to the relative movement of the object. The position is automatically detected, the distance measuring field is moved to track the movement of the object, and the focus is detected and adjusted based on this.

By the way, various types of so-called autofocus (hereinafter abbreviated as AP) devices that focus on a stationary subject that is not moving have been provided. For example, this type of AF device uses a contrast detection method, commonly known as a hill climbing method, in which the photographing lens is moved in the direction in which the value indicating the degree of focus increases, and when the peak position is detected, the camera stops there. The system is known. This contrast detection method takes advantage of the fact that the high frequency components in the video signal increase as the image comes into focus, and the high frequency components extracted from the video signal using a bandpass filter etc. are used to determine the degree of focus. It is detected as a signal indicating the

However, in this contrast detection type AF, since the defocus direction and defocus amount are unknown in one detection, the in-focus position can only be detected after passing through the in-focus point while constantly scanning. Therefore, it is necessary to detect the image many times, and near the in-focus point, so-called hunting is unavoidable, in which the camera passes through the in-focus point and then returns to the in-focus point, so it takes time for the focusing operation, and smooth operation is expected. could not.

In addition, with phase difference detection AF that detects the defocus direction and approximate defocus amount from data on two optical path lengths, it is possible to calculate the defocus direction and defocus amount with a small number of image signal detections. , the distance measurement accuracy is insufficient.

[Problems to be Solved by the Invention] However, the above-mentioned conventional examples disclose only one way to recognize a moving object or how to automatically track a moving object. However, no countermeasures are disclosed when a moving object moves too fast and deviates significantly from the in-focus position.

In other words, if the moving object deviates significantly from the in-focus position, the focusing speed of conventional contrast detection focus detection methods is slow, so the moving object disappears from the screen while the focus is being adjusted, making it difficult to maintain focus. There is a risk of becoming incapacitated. Therefore, when detecting a moving object, the challenge is how quickly to focus on the moving object and then track it. However, in the prior art, no improvement has been made in this regard.

Therefore, if an attempt is made to focus an arbitrary area of the screen using the phase difference detection method, the optical system becomes complicated. Furthermore, it is difficult to use the sensor used in the phase difference detection method as means for detecting changes in the relative position of a moving object using a video signal.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a moving object tracking device that can quickly and automatically track a moving object with a simple configuration.

[Means and effects for solving the problem] The moving object tracking device of the present invention includes a first focusing device that detects the relative positional relationship between two images that have passed through different optical paths and focuses on an object in a predetermined area. , a second focusing device that is controlled so that the high frequency component of the video signal obtained from the area sensor is maximized, and a relative position change detection device that detects a change in the relative position between the camera and the object in the predetermined area. and means for tracking the movement of the object by the second focusing device when the change in the relative position is detected.

[Example] The present invention will be explained below with reference to illustrated embodiments.

First, before giving a detailed explanation of the present invention, regarding the distance measurement principle used in the present invention, FIG. 2 shows a phase difference detection method, FIG. 3 shows a contrast detection method, and FIG.
The principle of each focus matching will be explained. And then,
An example in which sensors of each of these distance measuring methods are arranged in the optical system of a camera will be explained with reference to FIG.

FIG. 2 is an optical path diagram illustrating the principle of focus matching using the phase difference detection method. The principle of focus matching using this phase difference detection method is described in detail in, for example, Japanese Patent Laid-Open Publication No. 126517/1983, so only the main points thereof will be briefly explained here.

A pupil projection lens 32 is disposed at a predetermined focal plane 33 behind the photographing lens 2, or further behind the focal plane 33, and pupil splitting lenses 31 and 30 are disposed further behind it, respectively. Line sensors 7a and 7b having, for example, a CCD as a light receiving element are disposed on the imaging plane of each pupil splitting lens 31.30.

The subject images on each line sensor 7a, 7b approach each other in the direction of the optical axis O in the case of a so-called front bin, in which the image of the object to be tracked is formed in front of the planned focal plane 33; In each case, it becomes far from the optical axis 0. Further, when the two images are in focus, the distance between two corresponding points of the two images becomes a specific distance determined from the configuration of the optical system.

Therefore, the focal state can be determined by converting the light distribution patterns of the two images on the line sensors 7a and 7b into electrical signals and determining their relative positional relationship.

FIG. 3 is a diagram illustrating the principle of focus matching using the contrast detection method, and shows the relationship between the high frequency components output during detection and the focus matching position. Focus matching using the contrast detection method is described in detail in, for example, Japanese Patent Application Laid-Open No. 146080/1983, so only the main points thereof will be briefly explained here.

Focus matching using this contrast detection method is also called the hill-climbing method, and is a high-frequency region of the photoelectric conversion signal output from an area sensor formed by arranging many image sensors such as CCDs in a planar manner. Focusing is performed by detecting the maximum value of the frequency component. In Fig. 3, the horizontal axis indicates the focusing position of the photographing lens,
The closer the position on the horizontal axis is to the origin 0, the closer the object is in focus, and the farther from the origin, the more distant the object is in focus. Further, the vertical axis indicates the amplitude of the high frequency component of the video signal output from the area sensor.

Now, when the focusing device is at the position d1 corresponding to the subject distance, the focus is reached, the amplitude of the high frequency component is maximum, and the focus is shifted to either the near or far side from that position. It becomes a chevron characteristic that also decreases.

FIG. 4 is an optical layout diagram showing an example in which sensors for each of the distance measuring methods described above are arranged in an optical system of a single-lens reflex camera using a silver halide film.

In general, when comparing the sensor size of an area sensor consisting of a CCD image sensor used in a contrast detection type focusing device to the screen size when using a normal 35 mm film at full size, it is 2/3 of the normal screen size.
Since the sensor size of an inch CCD is approximately 1/4 of the screen size of a 35 mm film, the area sensor cannot be used as it is as an image signal input device for film printing. In other words, by simply arranging the CCD on the imaging plane of the photographic lens, only a part of the required angle of view can be captured on the CCD. Therefore, in FIG. 4, by inserting a reduction relay imaging optical system 44 that reduces the film image height to the CCD image height in the optical path, the CCD is placed on the imaging surface of the photographic lens as described above. This solves the problem that only a portion of the required angle of view can be captured by simply arranging the lenses.

In FIG. 4, the subject light transmitted through the photographing optical system 41 is divided into optical paths by a half mirror 42, and the light traveling straight is imaged on the surface of the film disposed on the imaging plane 45. Further, a part of the subject light reflected upward by the half mirror 42 is reflected backward once again by the reflection mirror 43 and enters the reduction relay imaging optical system 44. The optical path is further divided by a half mirror 46 disposed on the exit side of the reduction relay imaging optical system 44, and the downward optical path is formed by a CCD or the like that realizes focus matching using a contrast detection method over a planning angle. Even if the image is formed on the area sensor 5. This area sensor 5 is used not only for focusing by the above-mentioned contrast detection method but also for forming an image on an electric viewfinder, for example.

The optical path that passes through the half mirror 46 and goes straight backward includes a condenser lens 48, a separator lens 49.
A pupil splitting optical system 6 consisting of a field mask 50 and a line sensor 7 formed of COD or the like located near the rear of this optical system 6 and realizing focus matching using a phase difference detection method for the center of the screen are arranged. The subject image is formed on the sensor 7.

A moving object tracking device of the present invention that uses such n1 distance principle in combination will be specifically described below with reference to the drawings.

FIG. 1 is a block system diagram of an embodiment in which the moving object tracking device of the present invention is applied to a still video camera (hereinafter abbreviated as Sv camera).

In the figure, reference numeral 1 is a tracking target object 2, 2 is a photographing lens, 3 is an infrared cut filter, and 4 is a half mirror.

The light beam from the tracking target object 1 that has passed through the half mirror 4 forms an image on the area sensor 5 . The photoelectric conversion signal generated by the area sensor 5 is amplified by a preamplifier 9, and guided to a process circuit 17 and a bypass filter 10, which perform processing such as gamma correction and gain adjustment and convert it into a video signal.

The output of the process circuit 17 is guided to the magnetic head 21 via the recording circuit 18.

The rotation of the second motor 23 that drives the magnetic disk 22 is controlled by a servo circuit 24 . Further, the track control circuit 20 is a control circuit for moving the magnetic head 21 in the radial direction of the magnetic disk 22. On the other hand, the video output of the process circuit 17 is guided to a liquid crystal driver 25 and displayed as an image on a liquid crystal display section 26.

The output of the preamplifier 9 is passed through a bypass filter (H, P
, F) 10, A/D conversion is performed by the second A/D converter 11, and then stored in the image memory 12. The above image memory 12
A second microcomputer (CPU) 1 connected to
In step 3, calculations for performing focus matching are performed using high frequency components of the video signal, which will be described later. The second microcomputer 13 also generates a signal for superimposing the focus area of the object to be focused and supplies it to the liquid crystal driver 25.

On the other hand, the light flux from the subject reflected by the half mirror 4 is imaged on the line sensor 7 via the pupil division optical system 6 for phase difference detection, which is composed of a pupil projection lens, a pupil division lens, etc. . This line sensor 7 and the area sensor 5
is driven by the sensor driver 8. Further, the area sensor 5 is configured to be slightly vibrated by the first motor 100.

The system controller 19 controls the first motor 100
．． Process circuit 17. Recording circuit 18. Track control circuit 20. Servo circuit 24. A timing signal is sent to the liquid crystal driver 25 and the like to control the operation of each of these circuits.

The output of the line sensor 7 is transferred to the first A/D converter 14.
is guided to the first microcomputer 15 via.

The first microcomputer 15 performs focus detection calculations using a phase difference detection method, and also drives and controls the motor drive circuit 16.

The switch 27 is an AF lock switch for locking the subject to be focused. Further, reference numeral 28 is a release switch, and when this switch is closed, a video signal is recorded on the magnetic disk 22. Note that the first microcomputer 5 and the second microcomputer 1
The operation of this moving object tracking device is controlled in sequence while communicating with the moving object tracking device 3.

In FIG. 3, which shows the characteristics of high frequency components with respect to the focus matching position in focus matching using the contrast detection method, the area sensor 5 is slightly fluctuated in a sinusoidal manner as indicated by a or a2 by the first motor 00. . The fine fluctuation a1 is the fine fluctuation of the hand rear sensor 5 when the focusing device of the photographic lens 2 is located at a position d2 on the nearer side than the focusing position d1. 1- It undergoes amplitude modulation as shown in bl due to the change in cass. Also, the focus alignment device is at the focus position d.
At a position d3 on the far side, the amplitude is modulated as shown in b2 due to the focus change due to the slight fluctuation a.

As is clear from the figure, the phase of the amplitude modulation of bt and b2 is reversed depending on whether the focusing device is located closer or farther than the focusing position d1. Therefore, if the amplitude modulated signal shown in bl is synchronously detected with the reference frequency signal and the motor is driven in the direction of arrow C with this synchronously detected signal, and in the direction of arrow C2 with b2, focus alignment can be achieved. The device will always be stable at the point where the high frequency component is maximum.

The embodiment of the present invention configured in this way is different from the software aspect to the first embodiment shown in FIG. 5 and the second embodiment shown in FIG.
The operation of each of these embodiments will be explained below using FIGS. 5 to 7.

FIG. 5 is a flowchart of the moving object tracking device according to the first embodiment of the present invention, and FIGS. 6(A) and 6(B) are layout diagrams showing an example of the object to be tracked on the finder screen.

In FIG. 5, the photographer captures the object to be tracked in the focus area near the center of the screen (see FIG. 6(A)) and closes the AF lock switch 27 (see FIG. 1). Then, the first CPU 15 (see FIG. 1) operates to detect the distance to the object to be tracked using the phase difference method and drive the photographing lens 2, thereby performing focus alignment. That is, according to the phase difference method of focus detection, a wide defocus range can be detected with approximately one focusing operation, so focus alignment can be performed quickly.

Next, the video signal output from the area sensor 5 is analyzed to detect movement of the object to be tracked. The means for detecting the movement of the object to be tracked is described in detail in, for example, the Journal of the Television Society of Japan [Detection and Tracking of Moving Objects J, PRL78-10.1978, etc., so detailed explanation thereof will be omitted here.

When the object is moving, the focus detection area is tracked and superimposed display is performed as shown in FIG. 6(B). Therefore, when the movement of the object to be tracked is detected, the high frequency components of the video signal are transferred to the HPFIO.
(see Fig. 1), and thereby performs focus matching using the contrast method, that is, "maximum contrast detection drive."Next, it is detected whether the release switch 28 is on or not, and if it is on, After recording the video signal, the process ends.If the release switch 28 is not turned on, tracking of the object and focusing are continued repeatedly.

As described above, in the first embodiment, the photographer first uses the phase difference method to focus a predetermined area of the screen, often the focus area at the center of the screen, in accordance with the object to be photographed. Next, the area sensor 5 analyzes the photoelectrically converted video signal to detect the relative movement between the object in the predetermined area and the camera. The moving object is tracked using a contrast method that detects the maximum value of the frequency component.

In other words, the target object is detected by the phase difference detection method.
When the target object is moving, the video signal from the area sensor 5 is analyzed to detect the movement, and at the same time the contrast is detected. This method automatically tracks the movement of objects.

FIG. 7 is a flowchart of a moving object tracking device showing a second embodiment of the present invention. In the first embodiment described above, the object to be tracked is first focused using the phase difference detection method, and then the focus is adjusted by switching to the contrast method, so that both methods are temporally serially aligned and the focus is adjusted. Processing is in progress.

Therefore, according to this means, if the object to be tracked disappears from the focus area while focus matching is being performed using the phase difference method, tracking becomes impossible.

Therefore, in this second embodiment, the first microcomputer 15 performs focus matching using the phase difference detection method, and the second microcomputer 13 performs focus matching using the moving object tracking and contrast detection method, thereby performing processing in parallel. The aim is to move forward.

In FIG. 7, first, the object to be tracked is captured in the focus area near the center of the screen (see FIG. 6 (^)) and the AF lock switch 27 is turned on. Next, the second microcomputer 13 determines whether focus matching by contrast detection is possible, and if possible, the second microcomputer 13 performs focus matching and tracking.
It is left to the microcomputer 13 of That is, focus matching is performed using a contrast method using the area sensor 5.

If focus matching by contrast detection is not possible, focus matching is performed by phase difference detection. During focus matching using the phase difference detection method (while driving the lens), the second microcomputer 13 enables focus matching using contrast detection, and if a contrast peak is detected (focus matching), focus matching using the contrast method is performed. to move to. Note that the determination as to whether or not focus matching is possible through contrast detection may be made based on whether the contrast of the signal component is greater than or equal to a predetermined value, or may be determined based on the slight fluctuation a t of the area sensor 5 shown in FIG. 3 above. , a 2 may be determined based on whether a phase change of the high frequency signal is detected. Focus matching by contrast detection is the same as in the first embodiment. This second point mentioned above
According to the method of the embodiment, even high-speed objects can be tracked reliably.

[Effects of the Invention] As described above, according to the present invention, the defocus direction and defocus amount are calculated and quickly focused on a target object using a phase difference detection method in one detection. after,
When the target object is moving, the video signal from the area sensor is analyzed to detect the movement, and the movement of the target object is tracked using a contrast detection method, so that the moving object can be quickly tracked with a simple configuration. Can be done.

Further, since the output of the area sensor can be used also as a video signal, various remarkable effects such as high cost performance are exhibited.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the hardware configuration commonly applied to the first and second embodiments of the moving object tracking device of the present invention, and FIG. 2 is a phase difference diagram used in FIG. 1 above. An optical arrangement diagram of a pupil splitting optical system in a detection type focus matching device; FIG. 3 is a characteristic diagram of a high frequency component with respect to a focus matching position in a contrast detection type focus matching device used in FIG. 1; FIG. 4 is an optical layout diagram showing an example in which each sensor in the detection method shown in FIGS. 2 and 3 is applied to a single-lens reflex camera using a silver halide film, and FIG. 6(A) and 6(B) are arrangement diagrams within the viewfinder field of view showing an example of the object to be tracked on the finder screen. ) is a diagram showing the time when tracking is started, and FIG. 6(B) is a diagram showing the state during tracking. FIG. 187 is a flowchart of the operation of the moving object tracking device showing the second embodiment of the present invention. 1......Object to be tracked (object) 5...
...... Area sensor 6 ...... Pupil division optical system (first focus matching device) 7 ...... Line sensor (first focus matching device) 13 ...Second microcomputer (second focus matching device and relative position change detection means) 15...First microcomputer (first focus matching device)

Claims (1)

[Claims] (1) A first focusing device that detects the relative positional relationship between two images passing through different optical paths and focuses on an object in a predetermined area, and a high frequency component of the video signal obtained from the area sensor is maximized. a second focusing device that is controlled so that the change in relative position is detected; and a relative position change detection means that detects a change in the relative position between the camera and the object in the predetermined area, and when the change in the relative position is detected. A moving object tracking device for a camera, characterized in that the movement of the object is tracked by the second focusing device.